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Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 62 for “"self-excited"”.
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Self-excited electrostatic induction generator.
Massachusetts Institute of Technology. Dept. of Nuclear Engineering. Thesis. 1968. M.S.
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Self-excited vibrations of a spinning disk
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1995.
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Adaptive Control Methods for Non-Linear Self-Excited Systems
Self-excited systems are open loop unstable plants having a nonlinearity that prevents an exponentially increasing time response. The resulting limit cycle is induced by any slight disturbance that causes the response of the system to grow to the saturation level of the nonlinearity. Because there …
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Nonlinear oscillations of self-excited systems under multifrequency parametric excitation
A self·excited system with weak nonlinearities and multifrequency parametric excitation is investigated in this study. The method of multiple scales is used to analyze the system under four different resonances relating parametric excitation frequencies with the natural frequencies. In the first …
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Passive Broadband Targeted Energy Transfers and Control of Self -Excited Vibrations
Finally, experimental results are presented in connection to the theoretical investigation, and all the predictions on the instability suppression mechanisms are demonstrated experimentally. It is also revealed that the dry friction affects only the robustness of an instability suppression by …
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Nonlinear transient and steady state analysis for self-excited single-phase synchronous reluctance generator
… for alternative and renewable energy sources, self-excited induction and synchronous reluctance generators have attracted more attention for wind, tidal and hydro power generation applications. Compared to synchronous and DC generators, they have the advantages: they are brushless, they are …
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Performance of Self-excited Energy Harvesters with Tip Bodies of Non-circular Cross Section Shapes
<p>An experimental study on the performance of self-excited energy harvesters with non-circular tip body shapes has been performed. The two tip body shapes analyzed correspond to a half cylinder and a square cross section. Experiments are carried out in the wind tunnel to record the voltage output …
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Effect of self-excited acoustic perturbations on flow characteristics around rectangular cylinders with varied geometrical aspects
… susceptibility of such geometrical aspects to self-excited acoustic resonance in rectangular cylinders inside a high-speed wind tunnel. Experimental findings demonstrate a notable shift in both acoustic pressure and dynamic lift force during resonance excitation for rods characterized by an …
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An Experimental Investigation of Self-Excited Combustion Dynamics in a Single Element Lean Direct Injection (LDI) Combustor
<p>The management of combustion dynamics in gas turbine combustors has become more challenging as strict NOx/CO emission standards have led to engine operation in a narrow, lean regime. While premixed or partially premixed combustor configurations such as the Lean Premixed Pre-vaporized (LPP), Rich …
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The Effects of Porous Inert Media in a Self-Excited Thermoacoustic Instability: A Study of Heat Release and Reduced Order Modelling
… temporally resolved equivalence ratios during a self-excited instability. The experimental combustor has an optically accessible flame region which allowed for high speed chemiluminescence to be captured during the instability. Equivalence ratio values were calculated from a relation involving …
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A Theory for Wheezing in Lungs
… to improve our physical understanding of the self-excited oscillations observed when air flows through flexible tubes. In shell theory, the use of rotors from geometric algebra has enabled us to develop improved physical understanding of how changes of curvature, which are of direct importance …
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Turbulent flame microstructure, dynamics, and thermoacoustic instability in swirl-stabilized premixed combustion : measurements, statistics, and analysis
… and emissions constraints. Dynamic instabilities-self-excited, self-sustaining oscillations which link the combustor acoustics to the combustion process-can result in significant levels of thermal and mechanical stress on combustion systems, leading to reduced operational lifetime, potentially …
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The Acoustics of Cerebral Aneurysms
… In our simplified geometry, we identify that self-excited flow oscillations can generate sound at a distinct frequency. Periodic flow fluctuations have been observed in aneurysms by various studies. However, the potential of flow oscillations to cause aneurysm wall vibrations (hence sound) had …
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Influence of Bit Design on the Stability of the Rotary Drilling System
… exploration and production experience self-excited vibrations, which can lead to drilling dysfunctions such as bit bounce, stick-slip and whirling. These dysfunctions cause premature failure of drill bits and other components within the system, ultimately leading to increased cost of …
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Jet Fluid Mixing Control Through Manipulation Jet Fluid Mixing Control Through Manipulation of Inviscid Flow Structures
… flows. In this dissertation, two methodologies, self-excited nozzles and radially lobed nozzles, are studied and presented in order to enhance mixing in the near field of coflowing, subsonic, turbulent, free jet flows. The characteristics of the concentration field and the mixing performance are …
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Dynamic Modeling and Dynamic Analysis of the Boring Machining System
… long, slender boring bar make it susceptible to self-excited chatter during machining. The main focus of this thesis is directed at developing a system model which correctly describes the boring operation, applying modern control theory to perform dynamic cutting analysis, and exploring a …
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A microfabricated ElectroQuasiStatic induction turbine-generator
… under driven excitation of the six phases. Self excited operation was also demonstrated. Under self-excitation, no external drive electronics are required and sufficient power was produced to dimly light four LED's on two of the six phases. This is believed to be the first demonstration of …
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The effects of wall inertia and axial bending on instabilities in flow through an elastic-walled tube
… flow through flexible tubes is unstable to self-excited oscillations. Whittaker et al. (2010, Proc. Roy. Soc. A 466) solved an asymptotic model for the onset of self-excited oscillations in a long, thin-walled,flexible tube clamped between two rigid tubes, with a large axial tension. This …
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